The evolution of antimicrobial resistance (AMR) in pathogens has prompted extensive research to find alternative therapeutics. Plants rich with natural secondary metabolites are one of the go-to reservoirs for discovery of potential resources to alleviate this problem. Terpenes and their derivatives comprising of hydrocarbons, are usually found in essential oils (EOs). They have been reported to have potent antimicrobial activity, exhibiting bacteriostatic and bactericidal effects against tested pathogens. This brief review discusses the activity of terpenes and derivatives against pathogenic bacteria, describing the potential of the activity against AMR followed by the possible mechanism exerted by each terpene class. Finally, ongoing research and possible improvisation to the usage of terpenes and terpenoids in therapeutic practice against AMR are discussed.

Marine sponges are sessile invertebrates that can be found in temperate, polar and tropical regions. They are known to be major contributors of bioactive compounds, which are discovered in and extracted from the marine environment. The compounds extracted from these sponges are known to exhibit various bioactivities, such as antimicrobial, antitumor and general cytotoxicity. For example, various compounds isolated from Theonella swinhoei have showcased various bioactivities, such as those that are antibacterial, antiviral and antifungal. In this review, we discuss bioactive compounds that have been identified from marine sponges that showcase the ability to act as antibacterial, antiviral, anti-malarial and antifungal agents against human pathogens and fish pathogens in the aquaculture industry. Moreover, the application of such compounds as antimicrobial agents in other veterinary commodities, such as poultry, cattle farming and domesticated cats, is discussed, along with a brief discussion regarding the mode of action of these compounds on the targeted sites in various pathogens. The bioactivity of the compounds discussed in this review is focused mainly on compounds that have been identified between 2000 and 2020 and includes the novel compounds discovered from 2018 to 2021.

Nowadays, fish production through aquaculture and wild capture is escalating due to the higher fish protein demand for human consumption. Thus, the needs for fish products to be improved in scale and quality are becoming increasingly important to meet the nutrition requirements. The negative impacts caused by pathogens infection both in hatchery and grow-out ponds, have resulted in low aquaculture productivity and economic losses for the farmers. Therefore, a systematic study exploring relevant omics datasets through a systems biology approach will enable scientist to describe the complexity and characteristics of interactions in the host-pathogen network, leading to identifying new targets or biomarkers for diseases infection caused by bacteria, viruses, and parasites. The use of different approaches and emerging technologies as a powerful tool in obtaining a new knowledge for sustainable aquaculture production has been increasingly applied by many researchers over the years. In this paper, several omics approaches used to assess the fish immune response were reviewed. A brief description is provided for the omics approaches applicable to aquacultures, such as genomics, transcriptomics, proteomics, and metabolomics. Each tool used are contributes to develop better treatment and prevention strategies to overcome aquaculture disease due to the microbial infections. In genomics and transcriptomics analysis, their parallel approach involving gene expression studies play important role in identifying immune-related genes of the host, response to infectious diseases. While for proteomics and metabolomics approaches, these omics will provide information on the biomarker discovery and understanding the immune-related biosynthetic pathway during pathogen infection. Additionally, examples of the integrative analysis of multi-omics tools required for researchers to better understand the biological systems of aquatic animals especially fish, will also be provided.

House crows (Corvus splendens) in Selangor, Malaysia were examined for the presence of Campylobacter species, Salmonella species, Mycoplasma gallisepticum and Mycoplasma synoviae by serology, culture and pcr. For the detection of Campylobacter and Salmonella species swabs were taken either from the intestine or cloaca. For the detection of mycoplasmas, swabs were taken either from the choanal cleft or trachea for culture and pcr and serum samples were tested by the rapid serum agglutination (rsa) and monoclonal antibody-blocking elisa (mbelisa) for antibodies to M gallisepticum and M synoviae. For campylobacter, 25.3 per cent of the crows were positive by culture, and the species identified were Campylobacter jejuni and Campylobacter coli. No Salmonella species were isolated. Four of 24 swabs were positive for M gallisepticum dna but none gave positive results for M synoviae dna. No M gallisepticum or M synoviae antibodies were detected by rsa but 60 per cent of the sera gave positive reactions for M gallisepticum and 13 per cent gave positive reactions for M synoviae by mbelisa.

Antimicrobial resistance remains one of the most challenging issues that threatens the health of people around the world. Plant-derived natural compounds have received considerable attention for their potential role to mitigate antibiotic resistance. This study was carried out to assess the antimicrobial activity and mode of action of a monoterpene, 1,8-cineol (CN) against carbapenemase-producing Klebsiella pneumoniae (KPC-KP). Results showed that resazurin microplate assay and time-kill analysis revealed bactericidal effects of CN at 28.83 mg/mL. Zeta potential showed that CN increased the surface charge of bacteria and an increase of outer membrane permeability was also detected. CN was able to cause leakage of proteins and nucleic acids in KPC-KP cells upon exposure to CN and ethidium bromide influx/efflux experiment showed the uptake of ethidium bromide into the cell; this was attributed to membrane damage. CN was also found to induce oxidative stress in CN-treated KPC-KP cells through generation of reactive oxygen species which initiated lipid peroxidation and thus damaging the bacterial cell membrane. Scanning and transmission electron microscopies further confirmed the disruption of bacterial cell membrane and loss of intracellular materials. In this study, we demonstrated that CN induced oxidative stress and membrane damage resulting in KPC-KP cell death.